Solenoid valve systems for controlling flow of hydraulic or pneumatic fluid have been used in automated manufacturing equipment, production lines and numerous industrial applications. A plurality of solenoid valve housings, often referred to as manifold valve housings, manifold valve bodies, valve housings, valve bodies or valve housings, typically are mounted on a manifold having a plurality of passages for supplying fluid to the valves and providing passages to various outlet ports of each valve. Each solenoid of each valve housing typically is connected to an electronic system that controls operation of the several solenoids and valves. A typical manifold may contain many valve housings. The parts in a typical valve housing include gaskets, sleeves, mounting bolts and fasteners for attachment to other valve housings.
In the past, multiple valve housings were often mounted on a single manifold housing. The main disadvantage of the single manifold housing was that it limited the number of valve housings that can be assembled together, i.e. there was no adaptability to make the manifold longer to house more valve housings.
As a consequence, modular manifolds were developed. This modular manifold includes manifold modules mounted adjacent one another. The number of manifold modules used was adjustable up to a desired number. Each manifold module has a valve housing mounted thereon with the appropriate fasteners and seals.
The valve element used in these solenoid valve housings is typically a valve spool. Valve spools for pneumatic valves typically function as an air bearing. The valve spool is made from hardened 440C stainless steel is slidably received in the valve hole of the sleeve. The valve spool is finished to slidably fit within a valve hole and to slide virtually frictionless by floating on a thin air cushion as it reciprocates within the valve hole. The precise fit of the valve spool in the valve holes provides for a valve with an acceptably low leakage rate. The air cushion also provides for a long lasting, durable, and fast acting valve.
The valve housing is commonly made from aluminum. Aluminum is often used because it can be easily cast. Hardened 440C stainless is less amenable for casting and would require expensive machining. As a consequence of the harder metal of the valve spool, the valve housing up to now has not been able to directly receive the valve spool therein, but needs an intermediate member, often referred to as a sleeve. If the valve spool is received directly in the valve hole of the valve body, galling takes place which degrades the function of the valve. Furthermore, any contaminates within the valve housing can scratch the wall surface of the valve hole upon sliding of the valve spool within the valve hole which also degrades the function of the valve.
The sleeve prevents or reduces galling and scratching. The sleeve is made of hardened 440C stainless steel and is fitted into the valve hole with elastomer seals separating the different galleries. The sleeve needs to be properly positioned for appropriate alignment of the respective ports of the sleeve and the valve housing to assure the valve spool properly works. The sleeve has gaskets, o-rings or other seals seated on its exterior wall properly positioned to assure that the different ports in the valve housing are selectively sealed from one another about the perimeter of the sleeve so that the valve properly functions. The hardened 440C stainless steel prevents galling and scratching between the sleeve and valve spool.
The valve housing and the sleeve both need to have a certain wall thickness to maintain structural integrity. This requirement for structural integrity adds width to each valve housing. This added width is more noticeable, i.e. accentuated for smaller more compact valve housings.
Other parts, namely fasteners, for example nuts and bolts are commonly used to assembly the individual valve housings together. Separate adapters in the form of fittings are also mounted onto each housing to be connected to various input and output lines. Fasteners are also needed to mount the valve housing onto the manifold module. The fasteners, sleeve, and seals between the valve spool, sleeve, valve housings, and manifold modules, however add complexity and cost in machining and assembly to the finished valve unit.
What is needed is a monolithic. i.e. integrally formed combination manifold and valve housing with a reduced number of parts needed for it to be operational and connectable to other combination manifold and valve housings. For example, what is needed is a valve spool assembly that directly slidably mounts a valve spool without the intermediate sleeve or seal members. What is also needed is a monolithic module or modular unit that includes both a manifold section and a valve section. The monolithic housing slidably mounts a valve spool and provides internal passages to internal cross passages that extend laterally across the manifold section. What is also needed is a combination manifold and valve housing that is able to be simply mounted to an adjacent manifold and valve housing preferably without the need for separate fasteners. What is also desirable is a combination manifold and valve housing preferably made of hardened 440C stainless steel that slidably receives a valve spool. What is also desired is a combination manifold and valve housing that is made by additive manufacturing to provide integrally formed inlet and outlet fittings and made from 440C stainless steel. What is also desired is a valve housing made by additive manufacturing with a hardened 440C stainless steel section about an internal hole that slidably mounts a valve spool.